Abstraction & singleton


Hello, Basicly I need a class singleton and also include abstract
function? Is there any possibilty to achieve this structure?


More details
-------------------
There is 2 class
- class A that base class and also singleton,
- class B that derived from A also include abstract function

And I want to create a class that implements B class.

Class A {

void func() {
// do it something
}
}


abstract Class B extends A{

void func() {
super.func();
// add extra code
abst() ;
}

abstract abst() ;

}


Class C implement B {
abst() {
// add something
}
}


Thanks a lots
.